Swap getClientAddress().host call for the UNIXAddress compatible repl…

…acment, allowing tracing to correctly tag spans.

synapse/logging/opentracing.py

@@ -1070,7 +1070,7 @@ def trace_servlet(
         tags.SPAN_KIND: tags.SPAN_KIND_RPC_SERVER,
         tags.HTTP_METHOD: request.get_method(),
         tags.HTTP_URL: request.get_redacted_uri(),
-        tags.PEER_HOST_IPV6: request.getClientAddress().host,
+        tags.PEER_HOST_IPV6: request.get_client_ip_if_available(),
     }
 
     request_name = request.request_metrics.name